Social Behavior
Your dogs level of stimulation around other dogs could create an environment ranging from from frantic to friendly. The only real answer to creating a socially acceptable dog is to allow the opportunities for your dog to experience, interact with, and fail miserably in some cases in their interactions with other dogs. Just like you, your dog has personality traits and perferences - not to mention a job to do (which in some cases includes the dog acting unacceptably socially).
The only answer is exposure - and in some cases overexposure to environmental stimulus (or other dogs, people, etc). As owners, phrases like "my dog is afraid of men in hats" should be minimalized. If that were the case...the owner would have identified the problem and begun an exposure set up to have the dog desensitized to the sensation of men in hats. That part is our job as owners - to help with those situations.
When boarding your dog, make sure your dog is situated properly to recieve honest, caring, social interaction. See you soon.